Why

The lease of the space gives us three remotes to open the gate. We're coming up to 20 members now. So we decided to take one remote, mount it in reach of the gate and hook it up to a computer with a huawei modem.
The idea is: you call the number of the modem, it checks the caller id against a text file, and if it's in there it switches the remote. Best of all: 'just letting it ring one time' doesn't cost money and opens the door.
It's democratic because all our members have a cellphone, not all have a smartphone.

Next plans

Make a webinterface

do something with pgp keys and smartphone.

System architecture

All hardware will be divided in three cases:

A computer running the Gatekeeper software and connected to a Huawei modem and a Launchpad in a Terminal server case

An old Lantronix terminal server 1U acting as a PSU for reaching the gate and containing a TI Launchpad board.

A plastic IP65 junction box to be placed in front of the gate

A cat5 UTP cable will connect the junction box with the terminal server.

Circuit

The current circuit is a PNP transistor that, when base goes high (+5V), connects the Terminal PSU to a relais in the junction box that turns on the remotes (as if it's buttons were pushed)

Hardware

Lantronix case (obsolete)

Power supply

The original Lantronix PSU can be reused.
It gives the following outputs on a 6-pin molex:

Pin Number

Color

Voltage

1

RED

+12

2 & 3

BLUE

+5

4 & 5

BLACK

Ground

6

YELLOW

-5

TI Launchpad

Pinout on the Launchpad towards the gate opener:

Pin 1.7: white: 5V on/off (when high, remote gets "pushed")

Pin GND: black: ground (required to make sure we have a stable ground shared between the usb-computer connection and the terminal server PSU)

Stripboards

The two print boards, from RIGHT to LEFT: power connected to the inverter - now modified to act as passthrough (this pic is old), connected to the relais steering, connected to the ethernet cable (unclear).

Door opener tester (lost)

Simply a RJ45 male plug with a led attached to the brown pair. To be inserted into the connection of the remote. Allows developing software and hardware and testing the door without actually making the door go open. When the led is on, the remote is pressed.

Build in controle leds LED

The current version has three control leds build right in the power distribution/Launchpad box. When the system is on both leds on the right should be lit. If this is not the case the system will definitely not work. In this case the first thing you should check if the PSU is properly connected. When an authorized phone call is being received the red led on the left will blink.

Schematic

location

color

function

status

Right bottom

Blue

12V line is active

Always on

Right top

Green

5V line is active

Always on

Left bottom

Red

The signal to open the gate is being send

On intermittently when an authorized phone call is being received

IP65 Junction box

Remote

Stripboard

The stripboard contains the following:

Two RJ45 connectors

RJ45 connector on the bottom (IN) to receive power & signal

Relais

Remote

Double line male pins, with female connector connected to in ethernet cable